Isle of Man Solar Power, Is It Worth It?

Seen the adverts on Facebook?  Been preached to by an evangelist on social media telling you how solar and a heat pump is the end to all your energy worries?  Not worried about the environment but would love cheaper bills?  There is a lot of information and mis-information regarding solar panels but luckily for you we have first hand experience, having just paid out a small fortune for a solar plus battery setup on the Isle of Man here is our first hand experience to date.

First of all the house and solar setup.  We have installed a 5MWh solar array on to the equivalent roof space of a completely standard 3 bed semi-detached house located in Douglas, east coast of the Isle of Man.  5kWp of solar panels amounts to 14 individual panels, split 7 on each side of the roof.  This is about the absolute maximum size you could ever expect to get on a 3 bed semi (the type of house that makes up the vast majority of the housing stock on the Isle of Man, so it would have to work for us to be effective for the majority).  The house is orientated on approximately an north east to south west basis, so not ideal for solar and a large part of the reason we went for the maximum solar panel size and covering both sides of the roof.  This allows us to be generating from sun rise to sun set each and every day.

Finally to complete the setup we added a 9.5 kWh battery.  After some rough calculations this seemed a necessity for us as for most of the year our solar generation at the time we need it most (after 5pm) would be insufficient to cover cooking, TV, people being in the house etc.  The battery allows us to store what we generate during the best part of the day for use over the evening and through to the next morning.  9.5 was chosen based on our historical usage of around 8 units per day.  The total cost including installation for the whole solar and battery setup was just under £14500 (excluding the extra £1500 it cost us to satisfy Manx Utilities and the planning department).

What Does An Average Day With Solar Look Like In October?

May through to September you’re just about going to be fine with any solar setup, it’s what happens outside of that time that determines how much out of pocket you are going to be.  On an average day we would use 8 units of electricity.  We would also need to generate approx 2.5 units to cover the standing charge.  This gives us a target of 10.5kWh of generation per day, 365 days a year, to break even and have no electricity bills.  In July we could generate over 30kWh per day, August again was over 20kWh.  However September saw a huge drop off, just as our electricity needs went up (lighting).  September we were just about able to break even.  October we won’t.  That is around 5 months of the year where we can’t generate enough to cover usage plus the standing charge.

Isle of Man solar daily generation

It takes approximately an hour after sunrise for the generation to cover the passive usage of the house.  By 3 hours after sunrise we are generating enough to start seriously topping up the battery.  In October the generation starts to tail off at 3pm and is completely gone by around 6pm.  On the 14th of October on a day that was bright almost all day we generated around 9 kWh, virtually all of that was between 10am and 3pm.  We had a week this month where we didn’t generate over 6kWh on any day.  Without a battery solar for us would be a complete waste of time and money.  This is only October, we have November to February to navigate yet.  What about the electricity we fed back in to the grid during July and August when we were way over producing?  Have a guess at what the sum total of our credit over those 2 months was?  £40.  That is how much in credit we are to see us over the heaviest usage/low generation 4 months of the year.  IT IS NOT GOING TO COVER ITSELF.

IOM Solar

Does Solar Pay For Itself?

With an average electricity bill of around £1000 per year (including standing charge and VAT, standard for a 3 bed semi?) we need the solar and battery combination to eliminate our electricity bills completely for 14 years before our investment is paid back.  However it’s not going to completely remove our electricity bills, not even close, so in that case we are looking at between 16 and 18 years pay back.  The battery is only guaranteed for 5 years.  The panels will start to lose efficiency over time.  In theory in a worst case scenario we could end up having to spend as much on batteries (5 grand a go) as we would have on our entire electricity bills just to keep the solar viable.  I’m sorry to say that for a standard semi-detached house in terms of cost savings solar is a non starter.  There is an argument for saving the planet, there is no argument about it being value for money.

Would An Air Source Heat Pump Make Solar Viable?

In a word, no, not for us.  The traditional time for heating to be used is October through to Easter.  Exactly the time on the Isle of Man where our solar panels aren’t even covering our electricity usage without any heating involved.  Our 5 kWh solar array would generate enough on a nice day in December and January to run an ASHP for an hour each day, keeping in mind that in order to be efficient the ASHP has to be on almost constantly.  If we needed heating in July it would be perfect!  Not so much in winter unless you what to double or triple the amount of batteries and use the cheap rate electricity to top them up from the grid.  Even then for a house like ours that uses their traditional gas heating at most 3 hours a day it wouldn’t be cost effective.  This is before we get in to the costs involved in purchasing the ASHP and upgrading all the radiators.  There are no savings for us to be had in doing this.  Better to run a gas boiler for 3 hours.

Don’t get me wrong.  Solar could work really well for you, you just need a large detached house (bungalow would be perfect) with copious amounts of either roof area or land where you could put a very large solar array and maximise on the batteries.  It’s economies of scale and the break even point comes way above the space available to your average semi-detached home owner.

Could The Government/Manx Utilities Help To Make Solar Work?

It would be so simple, you just need to take away the need for batteries, lose the feed-in tariff and keep a balance for each property…electricity used vs electricity generated.  Charge everybody the same standing charge to cover connection and then everybody gets a balance every 3 months of consumption vs generation.  It’s the only way to make the expense of a solar installation viable on small properties on the Isle of Man.  Getting paid 1/3 of what it costs will not work.  If Manx Utilities acted as the battery all of a sudden it becomes worth the investment for everybody, solar stops being a rich persons play thing and becomes value for money to the majority.  It will never happen.

In summary then solar has not been a good investment for us, and if it’s not worked out for us then chances are it will not work out for the vast majority of similar properties on the Isle of Man.  We know we are not aligned ideally, but then who is?  Just to re-iterate this, below are screenshots showing generation from similar sized (3-5MWh) solar arrays located all over the Isle of Man up to the 16th of October 2023, from Peel, to Ramsey and from Port Erin to Douglas.  Please note that these figures over estimate production by around 10% but still all figures are within a few percent of each other and ours given the size of each array, the October drop off is real.  The chances of covering your electricity bills with solar arrays of this size being equally slim.

Isle of Man Solar Power, Is It Worth It? 3 Isle of Man Solar Power, Is It Worth It? 5 Isle of Man Solar Power, Is It Worth It? 7 Isle of Man Solar Power, Is It Worth It? 9



Want to see for yourself just how well Solar power performs on the Isle of Man?  Luckily we all end up with our data being shared whether we want it to or not, I’m guessing data protection doesn’t exist in the cowboy gold rush of solar installation.  You can check out live solar data for many locations around the Isle of Man on this website, just search for “Isle of Man”.



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